Although it first looks impossible, actually it is thanks to our eyes' persistence of vision (POV) effect,
and making use of multiplexing.
This technique is used in almost all electronics devices that visually presents something - from LEDs to
dot matrix LCDs, graphical LCDs and even CRT (those old bulky television screens that are based on cathode ray tubes).
Even our lamps in our house all take advantage of the our eyes' POV effect.
PIC16F628A which uses multiplexing technique to rotate 20 LEDs in various patterns.
I had this 20 LEDs camping light device which fell on the floor and its inside battery holders got broken.
Instead of throwing it away, I thought - hey, there are some nice 20 LEDs inside there, sitting on a simple
rounded PCBs! Lets try to used them as the base to a rotating lights project!
So, How do you control 20 LEDs? How would you animate them so they look as if they are rotating?